We are continuing to concentrate our research efforts on the determination of the role of hormones in controlling biochemical development in fetal tissues. We are trying to demonstrate that the 14S m-RNA stimulated by testosterone in human fetal liver in monolayer culture is the specific messenger for fetal hemoglobin in a protein synthesizing cell free system. In addition we have determined that fetal hemoglobin and alpha-fetoprotein are made in two different cells in humna fetal liver in monolayer culture. We are now trying to identify the cell types and to study the factors that stimulate alpha-fetoprotein synthesis. We have studied the effect of a variety of hormones on cell growth, cortisol synthesis from precursors and sulfation of dehydroisoandrosterone. These studies are now being extended to determine the action of c-AMP, the binding of I125-ACTH to the adrenal cells and the role of protein and RNA synthesis during stimulation of growth and steroidogenesis. We are continuing to study the binding of steroids to rabbit fetal lung receptors, the stimulation of dipalmitoyl lecithin synthesis (DPL) by a variety of hormones and the metabolism of epinephrine and the role of this pressor amine in DPL synthesis. We have completed our studies on the binding of glucocorticoids to rabbit fetal small intestine and we are now looking at the binding in the rat fetal small intestine. We are trying to correlate the receptor binding capacity with the ability to stimulate a number of enzymes in the fetal small intestine, i.e. alkaline phosphatase, sucrase and lactase. BIBLIOGRAPHIC REFERENCES: Stimulation of cortisol formation in human fetal adrenal cells in culture. Kan, K., Caspin, S. and S. Solomon. The Endocrine Society 57th Ann. Meeting, Abs. 13, 1975. McGuire, J.L., P.H. Brooks, R.F. McConnell, D.W. Hahn, G.D. Turner, J.P. DaVanzo and S. Solomon. Ovarian and adrenal function during the estrous cycle of the sow. Theriogenology 3:1, 1975.